Reverse circulation hybrid bit

ABSTRACT

A hybrid rotary drill having at least one fixed blade and at least one rolling cutter assembly is configured for reverse fluid flow from the annulus, through junk slots and into a fluid pathway system located substantially centrally to the bit body. The fluid pathway system may be located underneath a portion of the at least one fixed blade.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. Provisional Application Ser. No. 62/066,324, filed on Oct. 20, 2014, the contents of which are incorporated herein by reference for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

No Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The inventions disclosed and taught herein relate generally to hybrid drill bits having at least one fixed blade and at least one rolling cutter assembly; and more specifically related to a hybrid drill bit configured for reverse circulation.

2. Description of the Related Art

Rotary earth boring bits useful for oil and gas exploration and production have evolved considerably since the bi-cone bit developed by Howard Hughes, which had two rotatable cone-shaped cutting elements. Today, there are rotary bits with fixed or non-rotating blades with polycrystalline diamond cutters (PDC) mounted thereon. There are also rotary hybrid bits combining fixed blade cutting elements and rotating cutting elements. Most, but not all hybrid bits are modular in construction, in that the rotatable or rolling cutter elements are separate components coupled to the bit body by welding or other type of fastening.

Usually, the cuttings from the bottom and sides of the borehole are removed by drilling fluid (a liquid) that is pumped downhole from the surface. The cuttings are entrained in the fluid and carried by the drilling fluid to the surface for removal and disposal. Typically, the circulation path involves pumping drilling fluid down the hollow center pipe or drill string, forcing the fluid through jets or orifices in the drill bit to wash away the cuttings, and returning the cuttings-ladened fluid to the surface through the annulus.

It is also known to use a “reverse” circulation path in which the drilling fluid is pumped down the annulus to the drill bit where the cuttings are entrained in the fluid and the fluid is returned to the surface through the hollow drill pipe. Reverse is circulation requires that the drill bit be configured specifically to allow the cuttings-ladened fluid to pass through to the drill pipe. While reverse circulation has been used successfully with rotating cutter rotary bits, configuring a fixed blade bit or hybrid bit for reverse circulation present numerous issues not present in rotating cutter rotary bits, which issues have not heretofore been overcome.

The inventions disclosed and taught herein are directed to an improved modular hybrid bit configured for reverse circulation.

BRIEF SUMMARY OF THE INVENTION

As a brief summary of one of the many embodiments of the present inventions, a hybrid drill bit may comprise a body having at least one blade, each blade comprising a plurality of earth formation cutting elements; at least one rolling cutter assembly having a head onto which a cutter element is rotatably coupled; and a reverse circulation system adjacent a lower portion of the bit body and is configured to allow cuttings to pass there through and configured to maximize the load bearing capacity of the bit.

Other and further summaries of the invention are presented in the drawings, the text and the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following figures form part of the present specification and are included to demonstrate further certain aspects of the present invention. The invention may be better understood by reference to one or more of these figures in combination with the detailed description of specific embodiments presented herein.

FIG. 1 illustrates an end view of a typical hybrid rotary bit configured for conventional, or forward, circulation.

FIG. 2 illustrates a hybrid rotary bit configured for reverse circulation according to the present invention.

FIG. 3 illustrates another possible embodiment of a hybrid rotary bit configured for reverse circulation according to the present invention

FIG. 4 illustrates another possible embodiment of a hybrid rotary bit configured for reverse circulation according to the present invention.

FIG. 5 another possible embodiment of a hybrid rotary bit configured for reverse circulation according to the present invention.

FIG. 6 another possible embodiment of a hybrid rotary bit configured for reverse circulation according to the present invention.

While the inventions disclosed herein are susceptible to various modifications and alternative forms, only a few specific embodiments have been shown by way of example in the drawings and are described in detail below. The figures and detailed descriptions of these specific embodiments are not intended to limit the breadth or scope of the inventive concepts or the appended claims in any manner. Rather, the figures and detailed written descriptions are provided to illustrate the inventive concepts to a person of ordinary skill in the art and to enable such person to make and use the inventive concepts.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicants have invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present inventions will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. Lastly, the use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.

I have created a hybrid drill bit comprising a single or a plurality of fixed blades, at least one of which comprises a cutting element, and a single or a plurality of rolling cutter assemblies, at least one of which comprises a cutting element. A fluid pathway system adjacent the longitudinal axis of the bit is configured and provided to allow drilling cuttings to flow from the borehole through the pathway system and into the drill pipe. The fluid pathway system may comprise a single, centralized opening, such as a circle or an ellipse in cross section. Alternately, the fluid pathway system may comprise a plurality of openings of undetermined or determined shape, located on or about the longitudinal axis. In any of the embodiments, the opening(s) may be substantially planar (i.e., substantially two-dimensional) or three-dimensional, in that the opening(s) may have a longitudinal aspect to its shape. As taught herein, the fluid pathway systems may be designed and implemented in such fashion to maximize both the load bearing capacity of the drill bit and the flow area of the pathway. It will be appreciated that with this invention, fluid flow comes from the surrounding annulus, washes through the junk slots and enters the fluid pathway system on its way to the surface. The transition between the junk slots and the fluid pathway system may comprise hardfacing or other material systems configured to provide erosion resistance.

Turning now to FIG. 1, illustrated is a hybrid rotary drill bit 100 configured for forward circulation. Drill bit 100 may comprise a fixed blade 102 and a rolling cutter assembly 104. As illustrated in FIG. 1, the drill bit 100 has three fixed blades 102 and three rolling cutter assemblies 104. Fixed blade 102 may have at least one and preferably multiple cutting elements 106. Similarly, the rolling cutter assembly may have at least one and preferably multiple cutting elements 108. It will be appreciated that the term cutting element is used, even the process by which formation material is removed is not technically by “cutting.” Cutting elements 106 and 108 comprises all those elements known in the art to aid the removal of formation material regardless of the process used, including, but not limited to, cutting, shearing and crushing processes. Because drill bit 100 is configured for forward circulation, drill bit 100 comprises one or more fluid nozzles 110 and one or more fluid ports 116 adapted to allow drilling fluid (not shown) to pass there through and wash away drilling cuttings. FIG. 1 illustrates nozzles 110, 112 and 114 and ports 116, 118 and 120. For example, three ports are shown, each having a diameter of about 7/16 of an inch (about 0.15 in²). Three nozzles are also shown, each having a diameter of about ⅝ of an inch (about 0.31 in²).

FIG. 2 illustrates a hybrid rotary drill bit 200 configured according to the present is invention for reverse circulation. The drill bit 200 comprises at least one fixed blade 202 on which at least one cutting element 206, preferably, is located. The drill bit 200 also comprises at least one rolling cutter assembly 204, which preferably comprises at least one cutting element 208. Comparing drill bit 100 in FIG. 1 to drill bit 200 in FIG. 2, drill bit 200 does not utilize fluid nozzles 110 or fluid ports 116. Instead, drill bit 200 comprises a reverse circulation fluid path system 250, which in this embodiment preferably comprises a substantially round and substantially planar opening in the bit body substantially centered about the longitudinal axis of the bit 200. As an example of a particular embodiment, for a nominal 10 inch diameter drill bit, the fluid pathway system 250 may comprise an opening having an effective or average diameter of about 3 inches. Alternately, the fluid pathway 250 may have a cross-sectional area substantially the same as or larger than the drill bit shank bore (not shown). It will be appreciated that the fluid pathway system 250 is defined underneath the junction of the fixed blades 202. In other words, a portion of the fixed blades 202 adjacent the longitudinal axis may be cantilevered over the pathway 250.

FIG. 3 illustrates another hybrid rotary drill bit 300 configured according to the present invention for reverse circulation. The drill bit 300 comprises at least one fixed blade 202 on which at least one cutting element 206, preferably, is located. The drill bit 300 also comprises at least one rolling cutter assembly 204, which preferably comprises at least one cutting element 208. Drill bit 300 comprises a reverse circulation fluid path system 350 comprising three portions 350 a, 350 b and 350 c. Each of these portions may have a slot-like shape as illustrated, and in the embodiment illustrated in FIG. 3 are approximately 1 inch wide by about 2 inches long. Unlike the drill bit illustrated in FIG. 2, the drill bit of FIG. 3 provides blade 202 support at the bit center 322. It will be understood that fluid pathway slots 350 a, 350 b and 350 c converge into fluid communication with each other and with the bit shank bore (not shown) inside the bit body.

FIG. 4 illustrates yet another a hybrid rotary drill bit 400 configured according to the present invention for reverse circulation. The drill bit 400 comprises at least one fixed blade 202 on which at least one cutting element 206, preferably, is located. The drill bit 400 also comprises at least one rolling cutter assembly 204, which preferably comprises at least one cutting element 208. Drill bit 400 comprises a reverse circulation fluid path system 450 comprising a substantially round and planar opening, similar to system 25 in FIG. 2. However, the pathway system 450 comprises a replaceable insert 452 adapted to resist erosive wear of the cuttings-ladened fluid passing there through. As with the bit illustrated in FIG. 2, the cross-sectional area of the fluid pathway 450 is substantially equal to or greater than the cross sectional area of the bit bore shank.

FIG. 5 illustrates a hybrid rotary drill bit 500 configured according to the present invention for reverse circulation. The drill bit 500 comprises at least one fixed blade 202 on which at least one cutting element 206, preferably, is located. The drill bit 500 also comprises at least one rolling cutter assembly 204, which preferably comprises at least one cutting element 208. Drill bit 500 comprises a reverse circulation fluid path system 550 comprising a substantially centralized opening, such as described for drill bit 200 in FIG. 2. In FIG. 5, one of the rolling cutter assemblies has been removed to show that portion 550 a of pathway system 550. In this view, junk slots 560 and 562 are readily visualized. This view also shows how fixed blades 202 may be configured to both maximize the reverse circulation flow area and maximize blade strength.

FIG. 6 illustrates a hybrid rotary drill bit 600 configured according to the present invention for reverse circulation. The drill bit 600 comprises at least one fixed blade 202 on which at least one cutting element 206, preferably, is located. The drill bit 600 also comprises at least one rolling cutter assembly 204, which preferably comprises at least one cutting element 208. Drill bit 600 comprises a reverse circulation fluid path system 650 comprising a substantially centralized opening, such as described for drill is bit 200 in FIG. 2. In FIG. 6, one of the rolling cutter assemblies has been displaced to show that portion 650 a of pathway system 650. In this view, junk slots 660, 662 and 664 are seen. As can be appreciated from this figure and prior figures the hybrid bit of this invention may utilize modules, such as removable roller cutter assemblies 204. Also, the materials from which the bit body may be constructed can include steel, matrix materials and combinations.

All of the many possible embodiments of my inventions described herein may comprise modular rolling cutter assemblies that may be affixed to the bit body by mechanical fasteners, such as bolts or studs and nuts, or by chemical or metallurgical means, such as welding, brazing or amorphous diffusion bonding, or a combination of such systems. Further, embodiments may comprise fixed blades having cutting elements arranged to remove formation material adjacent the bit centerline, and/or arranged to remove formation material from a cone region to a gage region of the bit. The rolling cutter assemblies may be truncated in length and position such that the rolling cutter assemblies do not have cutting elements arranged to remove formation material in the cone and nose regions. The overlay of cutting elements of the fixed blades and the rolling cutter assemblies provide a substantially continuous cutting profile from cone to gage.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of invention. Further, the various methods and embodiments of the methods of manufacture and assembly of the system, as well as location specifications, can be included in combination with each other to produce variations of the disclosed methods and embodiments. For example, although the embodiments illustrated herein are symmetrical in that each bit has the same number of fixed blades as rolling cutter assemblies, my invention contemplates an asymmetrical arrangement of fixed and rolling cutter assemblies. Discussion of singular elements can include plural elements and vice-versa.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The inventions have been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicants, but rather, in conformity with the patent laws, Applicants intend to fully protect all such modifications and improvements that come within the scope or range of equivalent of the following claims. 

What is claimed is:
 1. A hybrid drill bit comprising: a bit body having a shank portion and at least one fixed blade; the shank portion having fluid bore of a predetermined cross sectional area; the at least one fixed blade comprising at least one cutting element configured to remove formation material; the bit body having at least one rolling cutter assembly disposed adjacent the at least one fixed blade and comprising at least one cutting element configured to remove formation material; at least one junk slot define between the at least one fixed blade and the at least one rolling cutter assembly; a reverse circulation fluid pathway system communicating from the at least one junk slot to the fluid bore so that fluid and cuttings can be flushed from the junk slots, through the fluid pathway system and into the shank bore.
 2. The hybrid drill bit of claim 1, further comprising three fixed blades and three rolling cutter assemblies.
 3. The hybrid drill bit of claim 2, further wherein each of the rolling cutter assemblies are truncated.
 4. The hybrid drill bit of claim 3, wherein the rolling cutter assemblies comprise a plurality of cutting elements configured to remove formation material from a shoulder and gage region, but not from a nose and cone region.
 5. The hybrid drill bit of claim 4, wherein the fixed blades comprise a plurality of cutting elements configured to remove formation material from a cone region to a gage region.
 6. The hybrid drill bit of claim 5, wherein at least one fixed blade is configured with at least one cutting element configured to remove formation material adjacent a centerline of the bit.
 7. The hybrid drill bit of claim 1, wherein the reverse circulation pathway is a substantially circular opening a lower portion of the bit body and substantially centered about a longitudinal axis of the bit.
 8. The hybrid drill bit of claim 7, wherein the reverse circulation pathway comprises hard facing to resist fluid erosion.
 9. The hybrid drill bit of claim 7, wherein the reverse circulation pathway comprises an erosion-resistant insert.
 10. The hybrid drill bit of claim 7, further comprising a plurality of fixed blades and wherein a portion of the fixed blades is cantilevered over the fluid pathway.
 11. The hybrid bit of claim 1, wherein the reverse circulation pathway comprises a plurality of openings in a lower portion of the bit body.
 12. The hybrid drill bit of claim 11, wherein the plurality of openings each comprises hard facing to resist fluid erosion.
 13. The hybrid drill bit of claim 11, wherein the plurality of openings each comprises an erosion-resistant insert.
 14. The hybrid drill bit of claim 11, further comprising a plurality of fixed blades and wherein a portion of the fixed blades adjacent a longitudinal axis of the bit is supported by the bit body.
 15. A method of drilling a subterranean bore hole comprising; running in the bore hole a reverse circulation hybrid drill bit; pumping a drilling fluid to the bottom of the bore hole through an annulus formed between a drill string and the borehole; establishing fluid circulation between the annulus and an interior of the drill string through the drill bit; rotating the drill bit to remove formation material; circulating the removed formation material from the borehole bottom, through the drill bit and into the interior of the drill string; wherein the hybrid drill bit comprises a bit body having a shank portion and at least one fixed blade; the shank portion having fluid bore of a predetermined cross sectional area; the at least one fixed blade comprising at least one cutting element configured to remove formation material; the bit body having at least one rolling cutter assembly disposed adjacent the at least one fixed blade and comprising at least one cutting element configured to remove formation material; at least one junk slot define between the at least one fixed blade and the at least one rolling cutter assembly; a reverse circulation fluid pathway system communicating from the at least one junk slot to the fluid bore so that fluid and cuttings can be flushed from the junk slots, through the fluid pathway system and into the shank bore. 